The new features are becoming reality in the next version of Hocus Focus. It should be available for beta testing in a few days. I had two clear nights this past week to test the program in a real Astrophotography experience. It worked great.

Focus
The first of these is the Focus Analysis module, shown below, that has three and a half focus metrics and a summary graph that really tells the story.

In the module above, the first star image is the current sample whose rate is controlled by the rate slider on the bottom. The second star image is an average of the last 5 samples with a master dark frame and the background subtracted. This second image is the source for the three focus metrics; FWHM, Radial Sum Value, and Peak. The FWHM takes both horizontal and vertical slices of the star image and the Full Width at Half Maximum is measured for both. The Radial Sum Value computes the distance of each pixel in the averaged and subtracted sample from the center of intensity and plots the sum value of increasing radii. In a way, this is like taking thousands of slices and integrating the values. The Peak value is important for two reasons. First, it will show that a star image has saturated which will confuse the previous metrics and second, it will show the brightest and thus sharper star image. The summary plots all of these metrics verses time and can show when you have reached or escaped critical focus.

What does all of this mean? The image above is focused and its peak is not saturated. You should strive for a screen like this but a slightly slimmer FWHM or a peak value of 250 might even be better. Depending on your optics the area of critical focus is either very small or small. By watching the "vs. Time" graph at the bottom as you approach focus, then pass focus, then return to focus the critical focus will be obvious.

Before you begin using the new features it is best to turn off the display of camera settings on the video. To do this press the video button once.

The first step to using the focus analysis is to "Take Darks". Place a lens cap on your camera or if you are using a telescope place it's cover or dark cloth over the business end and press the button "Take Darks." Hocus Focus will, in a few seconds, capture 16 images and average them creating a master dark. It will save this master dark in the program directory for future use. If you change anything in your setup just hit the "Take Darks" button again. Close the Focus Analysis window.

Click the Focus button again, to reload the focus analysis. The module should find the brightest point and begin analyzing focus. If the star moves too much, maybe you bumped the camera or telescope, Hocus may loose the star. Click the "Center" button and your mouse cursor will change to a cross hair type pointer. With this cursor click on the main Hocus window at the star to re-center the image.

The video image is not a true representation of the pixels in the camera. Usually a pixel in the video display is 6 to 7 times the size of a pixel in the camera. To account for this in the focus metrics click the "Pixel Config..." button and enter the resolution that you will actually use to shoot the subject. If you are using Digital Zoom, recommended, also enter the amount of digital zoom. Now the FWHM will be more accurate and similar to other systems values. [Note: pixels in a digital camera are much smaller than in most astronomical ccd cameras and thus your FWHM values will be much larger.]

Drift
How is that polar alignment? Is the PPEC working correctly. These things can be answered with the new drift analysis feature of Hocus Focus.

The graph above was created using data that was captured over 23 minutes with the new drift module. The log button will save the delta x and y values and the exact time in seconds at each sample. Both Periodic Error (the bumpy red) and Polar Alignment Error (both red and blue lines moving up) are evident in this representation of the data imported into Microsoft Excel. The actual Drift module looks something like this.

This screen is a mock up of the drift screen as screen capture was not possible because both focus and drift modules use the clipboard to steal images from the preview video. [Note: copy and paste operations are also not possible when either of these features are running.]

SnapShot
Using the same clipboard capture a snapshot can be grabbed from the video source and saved to the Hocus Focus directory. This is not a screen capture of the stretched video screen but a single frame grabbed from the video. Click the Snap button to take a picture any time. Shown below is an unfocused star as a collimation attempt. Looking at this image gave me an idea to try to automate the collimation process by measuring the "centeredness" of the dark spot and concentric rings. Maybe next version...

Samples
Finally some images using strictly the focus module to focus.

This image of the full moon was better focused with Hocus than those taken at the same time using the camera's autofocus.

I would have never achieved the critical focus necessary to get the tiny > mag. 15 stars near 61cyg in this image without using Hocus Focus.